As an embodiment of cutting tools, there is one which is used by attaching a cutting insert to a holder. Specifically, a seating surface of the insert is mounted on an insert pocket at a front end of the holder, and the insert is fixedly attached to the holder. For example, the insert has such a shape that a major surface thereof has an approximately polygonal tabular shape and a plurality of corner parts formed on one or both of the major surfaces are made into corner cutting edges. The cutting insert is used by attaching and reattaching the cutting insert to the holder so that these corner cutting edges are sequentially located at a tip side end of the holder.
As a known example of the material of the cutting insert, a coating layer is deposited on a surface of a base body composed of a hard alloy, such as cemented carbide and cermet. The coating layer is composed of a single layer of or a plurality of CVD layers which are deposited by CVD method, such as a titanium carbide layer, a titanium nitride layer, a titanium carbonitride layer, and an aluminum oxide layer.
A proposed method for a cutting insert includes depositing a coating layer on a surface of a base body, and thereafter polishing the surface of the coating layer located at a specific position. For example, Patent Document 1 discloses a cutting insert obtained by depositing a coating layer, followed by removing the coating layer deposited on a seating surface of the cutting insert by polishing.